Pressurized cylinders such as LPG cylinders comprise labels for inscribing certain information (i.e. date of production, date of filling, number of filling etc.) on the cylinders. Said labels are mainly positioned on the collar (preferably at the inner side of the collar) connecting the holding portion and body of the cylinders each other. In order to attach the label to the collar, at least one hole must be made on the said collar. In the prior art, one of the common applications utilized to make holes on a plate is to use a drill. However, sparkles may occur in making holes with the use of a drill, so such applications are not suitable for use in cylinders containing combustible gas such as LPG.